Communication devices such as wireless devices are also known as e.g. mobile terminals, wireless terminals, user equipments and/or mobile stations. Wireless devices are enabled to communicate wirelessly in a wireless telecommunications network, sometimes also referred to as a cellular radio system or cellular networks. The communication may be performed e.g. between two wireless devices, between a wireless device and a regular telephone and/or between a wireless device and a server via a Radio Access Network, RAN, and possibly one or more core networks, comprised within the wireless telecommunications network.
Wireless devices may further be referred to as mobile telephones, cellular telephones, or laptops with wireless capability, just to mention some further examples. The wireless devices in the present context may be, for example, portable, pocket-storable, hand-held, computer-comprised, or vehicle-mounted mobile devices, enabled to communicate voice and/or data, via the RAN, with another entity, such as another wireless device or a server.
The wireless telecommunications network covers a geographical area which is divided into cell areas, wherein each cell area being served by a base station, e.g. a Radio Base Station, RBS, which sometimes may be referred to as e.g. “eNB”, “eNodeB”, “NodeB”, “B node”, or BTS (Base Transceiver Station), depending on the radio technology and terminology used. The base stations may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. A cell is the geographical area where radio coverage is provided by the base station at a base station site. One base station, situated on the base station site, may serve one or several cells. Further, each base station may support one or several communication technologies. The base stations communicate over the air interface operating on radio frequencies with the wireless devices within range of the base stations.
In some RANs, several base stations may be connected, e.g. by landlines or microwave, to a radio network controller, e.g. a Radio Network Controller, RNC, in Universal Mobile Telecommunications System, UMTS, and/or to each other. The radio network controller, also sometimes termed a Base Station Controller, BSC, e.g. in GSM, may supervise and coordinate various activities of the plural base stations connected thereto. GSM is short for Global System for Mobile Communications.
In 3rd Generation Partnership Project, 3GPP, Long Term Evolution, LTE, base stations, which may be referred to as eNodeBs or eNBs, may be directly connected to one or more core networks.
UMTS is a third generation mobile communication system, which evolved from the GSM, and is intended to provide improved mobile communication services based on Wideband Code Division Multiple Access, WCDMA, access technology. UMTS Terrestrial Radio Access Network, UTRAN, is essentially a radio access network using wideband code division multiple access for user equipments. The 3GPP has undertaken to evolve further the UTRAN and GSM based radio access network technologies.
As may be seen above, the network topologies of different Radio Access Technologies, RAT, normally differ, i.e. comprises different kinds of network nodes. For example, the LTE RAN comprises only an eNodeB, while the WCDMA RAN comprises a central RNC being connected to a number of NodeBs.
However, as wireless telecommunication networks evolves and are upgraded to more recent or different RATs, new network topologies may arise which differs from the conventional network topologies, i.e. new wireless telecommunication networks with equipments normally comprised in different RATs. One example of this when LTE functionalities are located in the conventional RNC site of a WCDMA RAN to enhance the conventional RNCs functionality in terms of e.g. advanced load sharing or service awareness for the multiple RATs.
While it is possible for the equipments of the differing RATs to co-exist in the same access network, and serve separate user plane traffic flows based on which RAT each access points that is generating the user plane traffic flows is currently employing, it could be beneficial to explore possible advantages that may arise from such a wireless telecommunication network configuration comprising different RATs. In such cases, issues such as e.g. network capacity, transmission costs and latency performance, etc., should also be taken into consideration.